A ceiling balloon is used by
meteorologiststo determine the height of the base of clouds above ground levelduring daylight hours.The principle behind the ceiling balloon is a balloon with a known ascent rate (how fast it climbs) and determining how long the balloon rises until it disappears into the cloud.Ascent rate times ascent time yields the ceiling height.
How it is used
balloonis a small, usually red, (fluted) rubberballoon commonly measuring 76 mm (3 in) across prior to inflation, inflated to ~40 cm diameter. After inflation the balloon is taken outside and released. By timing the balloon from release until it enters the cloud a ceiling height can be obtained. When correctly inflated the balloon will rise at rate of 140 m/min (460 ft/min). The bases of clouds are very rarely flat and solid, so the ceiling height is not when the balloon disappears but when the colour begins to fade. The balloon can also be used to measure the vertical visibility into a layer of fogor blowing snow. In this case the balloon will begin to fade as soon as it is released, so the vertical visibility is when the balloon disappears. If the balloon is visible for a considerable distance into the cloud layer the observer should make note of it as it is of importance to aircraft.
The ceiling balloon is a reliable, safe and simple way to get an indication of the height of clouds. However, it does suffer from some disadvantages that the observer must be aware of.
Rainand wet snowmay slow the ascent of the balloon, giving a falsely high ceiling and high winds and poor visibility may cause the balloon to appear to enter the cloud before it actually does. As the balloon rises at a rate of 140 m/min (460 ft/min) it will take over five minutes for the balloon to reach 700 m (2300 ft). Beyond this height the ability to follow the balloon, even with binoculars, is poor, as even the slightest movement of the eye off the balloon will almost certainly ensure that it vanishes.
At night when it is not practical to use a balloon the
ceiling projectoris used. However, during twilight it may be impossible to use the ceiling projector and then a pibal (pilot balloon) light may be used. This is a simple flashlight bulb attached to a battery. To charge the battery it is immersed in water for three minutes and then tied to the balloon prior to inflation. These are rarely used today.
The balloons and associated equipment are usually stored in a cabinet mounted on a wall close to the gas cylinders. The cabinet has three doors one of which opens down and to it the filler stand is attached. At the top of the filler stand is a "L" shaped pipe with two rings, a small one on the bottom and a larger one on the top called the
inflationnozzle. The rings stop the tube from dropping through the stand or rising too far when the balloon is inflated. The top ring has several grooves cut into to help grip the balloon which is fitted to it.
At the bottom of the pipe is a weight that, when the precise amount of gas has been added, will lift to indicate the balloon is full. A rubber hose is attached to this pipe and passes through the filler stand twice. The first hole is larger than the tube to permit movement, while the second is used to hold the tubing in place.
From there the tube runs to a
needle valvethat controls the amount of gas flowing to the balloon. A second tube will then run from the valve to a regulator valve that is attached to the gas cylinder. This valve has two pressure gauges attached. One showing the total pressure remaining in the gas cylinder and the second showing the amount of gas flowing through the tubing. Typically the cylinder, which is made of steel and weighs about 140 lb (65 kg). It contains the equivalent of about 200 ft³ (5.7 m³) of gas at standard pressure, stored at a pressure of 2000 psi (14 megapascals) and will inflate approximately 120 balloons (according to a nominal diameter of 45 cm).
On the opposite side of the cabinet is space to store balloons, string and pibal lights. The gas used to fill the balloon is usually
heliumbut can also be hydrogen. However, due to its explosive nature in an oxygen atmosphere, hydrogen is rarely used.
The balloon is attached to the inflation nozzle and a piece of string is wound around the neck. After donning safety glasses and hearing protection a check is made to ensure the needle valve is fully closed. The main valve on the cylinder is then opened, followed by the regulator valve. Next, the needle valve is opened and the balloon begins to inflate. As the balloon reaches the correct size the inflation nozzle will begin to lift. At this point the needle valve is closed along with the regulator valve and cylinder vale. The string is then used to tie off the balloon neck to ensure that no gas can escape.
Caution must be used during inflation due to the occasional faulty balloon and its failure. If the person inflating the balloon is not wearing goggles or hearing protectors then eye or ear damage can result.
Timeline of hydrogen technologies
*Environment Canada - Atmospheric Environment Services, Technical Manual (TM07-01-01) Ceiling Balloon Equipment 76 mm (3 in).
Wikimedia Foundation. 2010.
Look at other dictionaries:
ceiling balloon — A small balloon used to determine the height of a cloud base or the extent of vertical visibility … Aviation dictionary
balloon flight — ▪ aviation Introduction passage through the air of a balloon that contains a buoyant gas, such as helium or heated air, for which reason it is also known as lighter than air free flight. Unmanned balloons have been used to carry meteorological… … Universalium
balloon — 1. noun sailing by in a balloon Syn: hot air balloon, barrage balloon; airship, dirigible, Zeppelin, blimp; weather balloon 2. verb 1) her long skirt ballooned in the wind Syn: swell (out), puff out/up, bulge (out), bag … Thesaurus of popular words
List of balloon uses — This is a list of uses of balloons*tiny **balloon catheter *small (volume of a few litres) **toy balloon **Water bomb ** Papier mâché **balloon animal **decoration **solar balloon **balloon mail as part of a balloon flight competition or to… … Wikipedia
Weather balloon — and student volunteer at NWS Weather Forecast Office, Riverton, Wyoming, USA … Wikipedia
Radiosonde — A GPS sonde, approx 220 × 80 ×75 mm (8.7 × 3.1 × 3 in) (with grounding station in background, used to perform a ground check and also recondition the humidity sensor) A radiosonde (Sonde is French for probe) is a unit for use in weather balloons… … Wikipedia
METAR — For the Israeli town, see Meitar. METAR is a format for reporting weather information. A METAR weather report is predominantly used by pilots in fulfillment of a part of a pre flight weather briefing, and by meteorologists, who use aggregated… … Wikipedia
Meteorological instrumentation — Galileo thermometer Meteorological instrumentation is the equipment used to sample the state of the atmosphere at a given time. Each science has its own unique sets of laboratory equipment. However, meteorology is a science which does not use… … Wikipedia
Topic outline of meteorology — For a more comprehensive list, see the List of meteorology topics. Meteorology is the interdisciplinary scientific study of the atmosphere that focuses on weather processes and forecasting. Meteorological phenomena are observable weather events… … Wikipedia
Outline of meteorology — See also: Index of meteorology articles Eye of Hurricane Isabel from the International Space Station, September 15, 2003. Meteorology is the interdisciplinary scientific study of the atmosphere that focuses on weather processes and forecasting.… … Wikipedia